Pension Benefit Obligations - Schedule of Underlying Assumptions for the Pension Plans (Details)	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
U.S.
Weighted-average assumptions to determine benefit obligation:
Discount rate (as percent)	5.01%	4.73%	5.76%
Weighted-average assumptions to determine net periodic benefit cost:
Discount rate (as percent)	4.73%	5.76%	5.40%
Expected long-term rate of return on plan assets (as percent)	6.25%	6.90%	7.00%
Int’l
Weighted-average assumptions to determine benefit obligation:
Discount rate (as percent)	5.83%	5.04%	5.65%
Salary increase rate (as percent)	2.81%	2.91%	3.06%
Weighted-average assumptions to determine net periodic benefit cost:
Discount rate (as percent)	5.04%	5.65%	5.27%
Salary increase rate (as percent)	2.91%	3.06%	3.48%
Expected long-term rate of return on plan assets (as percent)	5.51%	5.74%	6.04%